Method of laying bituminous pavement material



F. B. BOSCH.

METHOD OF LAYING BITUMINOUS PAVEMENT MATERIAL.

APPLICATION HLED JUNE 28, 1920.

1,366,? 1 1 Patented Jan. 25, 192 E.

UNITED STATES PATENT OFFICE.

FRANK B. BOSCH, 0F HARRISBURG, PENNSYLVANIA.

Application filed June 28, 1920.

To all whom it may concern Be it known that I, FRANK B. BosoH, a citizen of the United States residing at Harrisburg, in'the county ofiDauphin and State of Pennsylvania, have invented certain new and useful Improvements in Methods of Laying Bituminous Pavement Materials, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates, in the formation of pavement and the like, to the deposit on a base, distribution, and compression of asphaltic or other bituminous surface material that is plastic at the time of deposit.

Reference hereinafter is made to the accompanying drawing, of which- Figure 1 is illustrative of common methods of operation with and on bituminous roadsurface material; and

Fig. 2 is illustrative of a method provided by this invention.

It is the common practice, in laying bituminous or other thermally plastic road or pavement surfaces, to dump the material while hot at intervals on a base and to distribute it by shovels across and over the base at an angle of'substantia-llv 90 degrees to the curbs or other marginal boundaries of the roadway, as indicated by cross lines in Fig. 1, thereupon to distribute the material more evenly by raking, then to tamp the surface material along the gutters or other marginal boundary lines, then commencing at one side to roll the material by longitudinal movement of a roller as indicated by arrows 2 in Fig. 1 so that any transverse movement of surface material is toward the center of, and crown thereby preserved to, the roadway and to repeat the operation from the opposite side, and then to cross roll as indicated by arrows 3 in Fig. 1 or half-moon roll as indicated by lines 4 in that figure.

Rolling first at right angles across the waves of deposit of the material running substantially at right angles to the margins is partly responsible for wavy appearance of roadways when complete, as raking as ordinarily performed. breaks off the peaks of the waves of deposit to fill the valleys and uniform distribution of material, and therefore uniform density, is not obtained, except with the deep raking with tines of rakes that it is dilficult to get labor to practice. With the present methods, it would be preferable to give the hot material the cross roll first,

Specification of Letters Patent,

Patented Jan. 25, 1921. Serial No. 392,143.

but for the fact that such a method would tend to destroy the desirable crown effect in the finished roadway.

With a view of avoiding defects of the kind mentioned, this invention provides a method with which a better distribution of roller pressures on the surface material is obtained and the material, compressed to more uniform density with a uniform surface through out the roadway even when the first rolling is. parallel, or substantially parallel, with the longitudinal axis of the roadway and is performed from the sides toward the center.

By following the method now to be described, there is on the first rolling more angular movement than heretofore of the roller over the waves of deposit, whereby by the transverse movement of the plastic material there is prevented formation. of a wavy surface on material of uneven density that often results in depressions that hold water and other liquid that tend to make the roadway wear unevenly and increase the cost of maintenance.

In performing my process, plastic bituminous material is deposited on and distributed over the base at angles less than 90 degrees with respect to the roadway axis, preferably at an angle of approximately degrees, it being sufficient to obtain advantageous results that the angles of deposit and distribution shall not be at right angles or straight acrossthe roadway. but acute with respect to the axis thereof.

The lines of deposit and distribution may extend from one side of the base to be covered to the other, as indicated by lines 5 in Fig. 2, they may extend in different directions in alternate sections of the base as shown in that figure, they may extend in different directions in a section as indicated by lines 6 in that figure meeting between the sides, or any or all of such dispositions may be used, so longas the lines or directions of deposit and distribution are at acute angles to the direction of movement of a roller when traveling parallel or substantially parallel with the roadway axis.

The surface material is distributed in this manner in order that, when a roller is moved thereover longitudinally of the roadway, which'is the preferable and usual direction of movement in first rolling. for the reasons hereinbefore set forth. the roller will not operate on waves of deposit at right angles, but at acute ones. By first operating the roller at acute angles with respect to the waves of deposit or distribution, the surface material is compressed to more uniform density and with a more uniform surface through its transverse movement than with the usual procedure. This result can only be partially obtained with the usual methods, and then unsatisfactorily as hereinbefore explained, by cross rolling. which is performed after the longitudinal first rolling that is apt to leave the material with a density and surface that are not uniform throughout.

By my method the double advantage of longitudinal rolling in direction and cross rolling in effect is obtained on the first roll-' ing. Thereafter. on cross rolling the material deposited or distributed angularly, the roller travels at substantially right angles to the waves of distribution when proceeding in the direction of arrow 7 in Fig. 2 and substantially parallel therewith when proceeding in the direction of arrow 8 in that figure, in both cases the cross rolling being at acute angles with respect to the first or longitudinal rolling. Gross rolling parallel with the waves is practically impossible to perform when the waves are at right angles to the roadway axis, except on the widest roadways with wide rigid gutters. In moon rollingas indicated by arrows 9 in Fig. 2-the roller strikes the waves practically at right angles.

The arrow 7' indicates the direction of roller operation in its late stages at substantially right angles with respect to the waves, which is the direction followed in the early stages of rolling in accordance with common practice. Considerable advantage is obtained by this delayed application of the right-angle treatment, as the material already has been brought to uniform density and even surface by the first rolling parallel with respect to the roadway axis.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. A method of laying bituminous pavement-surface material that includes distribution of the material in directions at acute angles to the longitudinal axis of a base to be covered, and then first rolling the material in a direction substantially parallel with said axis.

2. A method of laying bituminous pavement-surface material that includes distribution of the material in directions at acute angles to the longitudinal axis of abase to be covered, and then first rolling the material in a direction at an acute angle with respect to that of distribution. v

3. A method of laying bituminous pavement-surface material that includes distribution of the material at acute angles to the longitudinal axis of a base to be covered, then first rolling the material in a direction substantially parallel with said axis,-a11d then rolling the material in other, directions.

4. A method of laying bituminous pavement-surface material that includes distribu- FRANK B. BOSCH. 

